Circadian Activity Rhythms Tied to Cognition in Older Women

FRIDAY, Dec. 9 (HealthDay News) -- Older, healthy women with decreased circadian activity rhythm amplitude and robustness, and those whose timing of peak activity occurs later in the day, are more likely to develop dementia and mild cognitive impairment (MCI), according to a study published online Dec. 7 in the Annals of Neurology.

Gregory J. Tranah, Ph.D., from the California Pacific Medical Center Research Institute in San Francisco, and colleagues examined whether circadian activity rhythms were prospectively associated with incident dementia or MCI in 1,282 healthy, community-dwelling older women (mean age, 83 years). Data were collected using wrist actigraphy for a minimum of three 24-hour periods. After a follow-up of 4.9 years, a battery of neuropsychological tests were performed, and an expert panel assessed clinical cognitive status (dementia, MCI, normal). The results were adjusted for multiple variables.

The investigators found that 15 and 24 percent of the women developed dementia and MCI, respectively. Older women with decreased activity rhythms were more likely to develop dementia or MCI when women in the lowest quartile of amplitude and rhythm robustness were compared to those in the highest quartiles of amplitude and robustness, (odds ratio [OR], 1.57 for both). Women whose timing of peak activity occurred later in the day (after 3:51 p.m.), had a higher risk of dementia or MCI than women with average timing (1:34 p.m. to 3:51 p.m.) (OR, 1.83).